Staircase for vehicle interior



1.1 is front, left, top-side view of the staircase for a vehicle interior showing my new design;

1.2 is a front-side view thereof;

1.3 is top-side view thereof;

1.4 is left-side view thereof; and

1.5 is a right-side view thereof.

Broken lines show features which form no part of the claimed design. 

CLAIM The ornamental design for a staircase for a vehicle interior, as shown and described. 